Self-propelled drive and cutter using same

ABSTRACT

A self-propelled cutter has a gear assembly to provide both downward and forward force on a material to be cut. A gear assembly includes a drive input gear that engages with a transfer gear and propulsion gear engaged with the transfer gear by a lever arm. The drive gear and transfer gear are coupled and fixed to the cutter body but the propulsion gear rotates about the transfer gear via the lever arm. This gear assembly enables the propulsion gear to move as required to provide both downward and forward force on a material to be cut, such as a cast. A self-propelled cutter may have a drive input that is coupled with a drive input device, such as a crank or an electric motor. A cutter may have a first gear assembly on a first side of the cutter body and a second gear assembly on a second side.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional application No.62/798,043, filed on Jan. 29, 2019, entitled Self Propelled drive andCutter Using Same; the entirety of which is hereby incorporated byreference herein.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to a self-propelled cutter having a fixed bladeand gear assembly to drive the cutter across a material to be cut, suchas a cast.

Background

Self-propelled cutters often have moving blades that rotate or vibrateto cut. This can be dangerous when the material to be cut is a cast.Rotating blades can easily cut the patient, adding significant risk totheir use, and as such must be guarded carefully. Vibrating bladesgenerate excessive noise, dust, and heat. The noise often scares youngerpatients. The dust must be captured and removed, and in some cases, theheat generated can result in burns to the patient. Fixed blade cutterstypically require manual force to cut through the material.

SUMMARY OF THE INVENTION

The invention is directed to a self-propelled cutter having anarrangement of gears to provide both downward and forward force on amaterial to be cut to propel the cutter across the material. Anexemplary gear assembly includes a drive input gear that engages with atransfer gear and propulsion gear engaged with the transfer gear by alever arm. In an exemplary embodiment, the drive gear and transfer gearare coupled and fixed to the cutter body but the propulsion gear rotatesabout the transfer gear via the lever arm. This exemplary gear assemblyenables the propulsion gear to move as required to provide both downwardand forward force on a material to be cut, such as a cast. In someembodiment, the transfer gear may be directly coupled with the driveinput, thereby eliminating the need for the drive gear.

An exemplary self-propelled cutter has a drive input that is coupledwith the drive gear or gears and a drive input device, such as a crankor electric motor, may be coupled with the drive input to rotate thedrive gear and thereby drive the other gears in the gear assembly. In anexemplary embodiment, the drive input extends out of one of the first orsecond sides of the cutter body and the drive gear and transfer gearhave rotational axes that are parallel. In an exemplary embodiment, thedrive input extends out the front or back of the cutter body and thedrive gear is a worm gear having a rotational axis that is orthogonal tothe transfer gear's rotational axis. An exemplary drive gear hasengagement teeth that engage with engagement teeth of the transfer gear.

An exemplary propulsion gear is configured at an offset angle to avertical axis and trails the transfer gear, whereby the rotational axisof the propulsion gear is located back from the rotational axis of thetransfer gear with respect to the cutter body. The offset angle may beabout 0 degrees or more, about 15 degrees or more, about 25 degrees ormore, about 35 degrees or more, about 90 degrees or less, about 75degrees of less, about 60 degrees or less, or any range between andincluding the offset angles provided such as from about 0 degrees toabout 60 degrees. This offset angle may be limited by stops, afront-stop and a back-stop, or springs, that are part of or coupled tothe cutter body.

An exemplary propulsion gear has engagement teeth that engage withengagement teeth of the transfer gear. An exemplary propulsion gear hasa tread that makes contact with the material to be cut and is anoutermost radial extension from the axis of rotation. An exemplary treadmay be the engagement teeth of the propulsion gear or a separate ring ordisc that is coupled with the propulsion gear and extends out moreradially than the engagement teeth of the propulsion gear. The tread mayengage with the material to be cut and thereby keep the engagement teethof the propulsion gear free of debris. An exemplary tread may bedetachably attachable which may allow a user to change the type of treadused to accommodate the material to be cut.

An exemplary self-propelled cutter has a first gear assembly on a firstside of the cutter body and a second gear assembly on a second side ofthe cutter body. A first side of the cutter body is the side having thedrive input. A drive input may be configured to drive both a first andsecond drive gear and thereby drive both gear assemblies. Two treads mayenable the cutter to be propelled evenly across the material withrespect to the central blade and may be preferred. A self-propelledcutter with a tread or engagement teeth only on one side of the blademay have a tendency to walk away from the side having the tread. In anexemplary embodiment, a self-propelled cutter has one gear assembly buthas a propulsion gear assembly with two treads, whereby the cutter bodyhas a propulsion gear body recess to accommodate an extension of thepropulsion gear from the first side to the second side of the cutterbody. A second tread may be coupled to this propulsion gear extensionand provide uniform propulsion on either side of the blade.

An exemplary self-propelled cutter comprises a blade that is fixed andtherefore not a rotating or reciprocating blade. The blade may becoupled to a blade assembly and may be detachably attached to the cutterbody. A blade fastener may be coupled with the cutter body and allow auser to disengage the blade or blade assembly to change out the blade asrequired. The blade may be a razor blade and may be a commoncommercially available type of blade and the blade assembly may beconfigured to receive the blade. A blade, as used herein, is any cuttingimplement and may be a fixed cutting implement having a sharp cuttingsurface and the blade may be detachably attachable to the foot or be anintegral part of the foot, such as a sharp edge of the foot.

An exemplary self-propelled cutter comprises a foot that is configuredbelow the blade and guides the material to be cut up and over the blade.The material to be cut may be captured and pinched between the foot andthe propulsion gear or tread, and the cutter propels itself along thematerial to be cut. Therefore, an exemplary foot extends outward fromthe blade. An exemplary foot extends forward the blade and protects auser from exposure to the blade. An exemplary foot has a width that isabout 30 mm or less, about 20 mm or less, about 10 mm or less, about 5mm or less, about 4 mm or less, about 3 mm or less and any range betweenand including the foot widths provided. It is desirable to reduce thefriction required to propel the self-propelled cutter over material tobe cut and a wider foot may increase the friction.

It is to be understood that this drive mechanism and particularly theorientation of the drive gear with respect to the transfer gear, wherebythe drive gear rotates about the transfer gear, could be used on anynumber of mechanical devices requiring driving of an object, such asalong a plane or direction. Such devices may include any type ofself-propelled object including a vehicle, lawn equipment, or toy, ordevices that propel an object such as a tool, a table or band saw, andthe like.

An exemplary self-propelled cutter may be portable in size such that itcan be carried easily by a single person and may have a width and/orlength of about 30 cm or less, about 20 cm or less, about 10 cm or lessand any range between and including the length values provided.

Self-propelled, as used herein, describes a tread that pulls thematerial to be cut through the foot of the cutter; a self-propelledcutter may have a manual drive input or a motorized drive input.

The summary of the invention is provided as a general introduction tosome of the embodiments of the invention, and is not intended to belimiting. Additional example embodiments including variations andalternative configurations of the invention are provided herein.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention, andtogether with the description serve to explain the principles of theinvention.

FIG. 1 shows a second side of an exemplary self-propelled cutter havinga drive gear engaged with a transfer gear and the transfer engaged witha propulsion gear by a lever arm.

FIG. 2 shows a perspective view of a second side of an exemplaryself-propelled cutter having a drive gear engaged with a transfer gearand the transfer engaged with a propulsion gear by a lever arm; thedrive input is on the opposing side.

FIG. 3 shows a perspective view of a first side of an exemplaryself-propelled cutter having a drive input extension extending to thefirst side to drive the drive gear.

FIG. 4 shows a perspective view of a first side of an exemplaryself-propelled cutter having a drive gear coupled to the drive inputextension.

FIG. 5 shows a back view of an exemplary self-propelled cutter having acrank as a drive for the drive input.

FIG. 6 shows a back view of an exemplary self-propelled cutter having aT-handle as drive for the drive input.

FIG. 7 shows a perspective view of an exemplary self-propelled cutterhaving a set of gears, or gear assembly, on both the first and secondside of the housing body.

FIG. 8 shows a front view of an exemplary self-propelled cutter having aset of gears, or gear assembly, on both the first and second side of thehousing body.

FIG. 9 shows a front view of an exemplary self-propelled cutter having asingle gear assembly and a propulsion gear having a propulsion gearextension that extends from a first side of the cutter body to thesecond side of the cutter body.

FIG. 10 shows an expanded perspective view of an exemplaryself-propelled cutter having two propulsion gears configured on opposingsides of the blade to propel material through the cutter.

FIG. 11 shows a second side of an exemplary self-propelled cutter havinga drive gear engaged with a transfer gear and the transfer engaged witha propulsion gear by a lever arm and a tread extending out from theengagement teeth of the drive gear.

FIG. 12 shows a first side of an exemplary self-propelled cutter havinga worm gear engaged with a transfer gear and the transfer engaged with apropulsion gear by a lever arm.

FIG. 13 shows a perspective view of an exemplary self-propelled cutterwith the cover removed to expose the internal drive assembly thatutilizes a first drive gear driven by the handle and a first transfergear on a first side or drive side that is coupled with a secondtransfer gear that drives a second side interface gear, wherein theinterface gear is coupled to the second propulsion gear about apropulsion axle.

FIG. 14 shows an enlarged perspective view of the foot and blade as wellas the propulsion gears.

FIG. 15 shows a front view of an exemplary self-propelled cutter withthe cover removed to expose the internal drive assembly.

FIG. 16 shows a top view of an exemplary self-propelled cutter with thecover removed to expose the internal drive assembly.

FIG. 17 shows a second side view of an exemplary self-propelled cutterwith the cover removed to expose the internal drive assembly; thepropulsion gear is down in a drive configuration.

FIG. 18 shows a second side view of an exemplary self-propelled cutterwith the cover removed to expose the internal drive assembly; thepropulsion gear is up as the handle is not being turned.

FIG. 19 shows a perspective view of an exemplary self-propelled cutter.

FIG. 20 shows a perspective view of an exemplary drive assemblyconfigured in the exemplary self-propelled cutter shown in FIGS. 13 to19.

FIG. 21 show a perspective view of an exemplary drive assembly shown inFIG. 20 with a spring configured in the spring recess.

Corresponding reference characters indicate corresponding partsthroughout the several views of the figures. The figures represent anillustration of some of the embodiments of the present invention and arenot to be construed as limiting the scope of the invention in anymanner. Further, the figures are not necessarily to scale, some featuresmay be exaggerated to show details of particular components. Therefore,specific structural and functional details disclosed herein are not tobe interpreted as limiting, but merely as a representative basis forteaching one skilled in the art to variously employ the presentinvention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

As used herein, the terms “comprises,” “comprising,” “includes,”“including,” “has,” “having” or any other variation thereof, areintended to cover a non-exclusive inclusion. For example, a process,method, article, or apparatus that comprises a list of elements is notnecessarily limited to only those elements but may include otherelements not expressly listed or inherent to such process, method,article, or apparatus. Also, use of “a” or “an” are employed to describeelements and components described herein. This is done merely forconvenience and to give a general sense of the scope of the invention.This description should be read to include one or at least one and thesingular also includes the plural unless it is obvious that it is meantotherwise.

Certain exemplary embodiments of the present invention are describedherein and are illustrated in the accompanying figures. The embodimentsdescribed are only for purposes of illustrating the present inventionand should not be interpreted as limiting the scope of the invention.Other embodiments of the invention, and certain modifications,combinations and improvements of the described embodiments, will occurto those skilled in the art and all such alternate embodiments,combinations, modifications, improvements are within the scope of thepresent invention.

As shown in FIG. 1, an exemplary self-propelled cutter 10 is in anupright position and has a drive assembly 14 including a drive gear 40engaged with a transfer gear 50 and the transfer engaged with apropulsion gear 60 by a lever arm 70. The lever arm 70 enables thepropulsion gear 60 to rotate about the transfer gear 50 as required todrive the material through the cutter 10. As indicated by the boldarrows, the propulsion gear 60 is driven indirectly by the drive gear40, which is driven by the drive input extension 32 that extend throughthe cutter body 20. The propulsion gear 60 provides downward andhorizontal forces on the material 17 to be cut. The rotational axis 61of the propulsion gear 60 and lever arm axis 71 are configured at anoffset angle 77 from the vertical axis 21, extending though the rotationaxis 51 of the transfer gear 50. This offset angle and ability to pivotabout the transfer gear 50 enables the propulsion gear 60 toself-regulate downward and horizontal forces on a material movingthrough the cutter 10. The engagement teeth of the propulsion gear 60may grip the material to be cut and pull it through the cutter 10. Thepropulsion gear may have a tread 68 that extends around the engagingpropulsion gear 60, wherein the tread extends radially outward beyondengagement teeth of the propulsion gear 60. The tread may provide bettergrip on the material to be cut 17 and may prevent debris from gettinginto the propulsion gear 60. An exemplary blade 80 is detachablyattached to the cutter body 20 by a blade fastener 84, such as a bolt.The blade assembly 82 may then be removed and the blade may be exchangedfor a new blade. A foot 90 is configured to extend under the material tobe cut 17 and direct it over the blade 80.

As shown in FIG. 2, an exemplary self-propelled cutter 10 is shown. Thedrive input 30 is shown on the first side 28 of the cutter body 20. Afirst set of gears, or gear assembly 15, is shown on the second side 29of the cutter body 20. The rotational axis 41 of the drive gear 40 andthe rotational axis 51 of the transfer gear 50 are shown. The driveinput extension 32 extends from the drive input 30, through the cutterbody 20 to the second side 29 of the cutter body 20. The rotational axis61 of the propulsion gear 60 will move in an arc about the rotation axis51 of the transfer gear 50, due to the lever arm 70 linkage. The leverarm 70 holds the transfer gear 50 and propulsion gear 60 in engagementwith each other. The foot 90 extending in front of the blade 80 is moreclearly seen in this view. The propulsion gear 60 can rotate between thefront-stop 23 and back-stop.

Referring now to FIGS. 3 and 4, an exemplary self-propelled cutter 10has a drive input 30 comprising a drive input extension 32 extendingfrom the first side 28 to the second side 29 to drive the drive gear 40;shown attached to the drive input extension in FIG. 4. The transfer gear50 is coupled with a transfer gear bearing 54 that is coupled to thecutter body 20 via a transfer gear mount aperture 52. As shown in FIG.4, the cutter body 20 may have a propulsion gear body recess 65 to allowa propulsion gear extension to extend across or through the cutter body20 to couple with a second tread. Note that the back end of this recess65 provides the back-stop 26 to prevent the propulsion gear 60 fromrotating too far back about the transfer gear. The cutter body 20 has alength from the front 22 to the back 24 and a height from the bottom 27to the top 25. As shown in FIG. 3, the drive input is configured on aside that may be conducive for a left handed person to manipulate a handoperated input, such as a handle.

As shown in FIG. 5, an exemplary self-propelled cutter 10 has a driveinput device 31, such as a crank 34, to provide a drive to the driveinput 30. The crank is coupled with the drive input and a handle 35enables manually driving the gear assembly on the second side 29 of thecutter body 20. A cover 12 is coupled to the cutter body 20 and extendsover the gear assembly for safety.

As shown in FIG. 6, an exemplary self-propelled cutter 10 has a driveinput device 31, such as a crank 34, to provide a drive to the driveinput 30. The crank is coupled with the drive input and a handle 35, at-handle 36, that enables manually driving the gear assembly on thesecond side 29 of the cutter body 20. A cover 12 is coupled to thecutter body 20 and extends over the gear assembly for safety.

Referring now to FIGS. 7 and 8, an exemplary self-propelled cutter 10has a gear assembly on both the first side 28 and second side 29 of thehousing body 20. A single drive input 30 drives both the first andsecond drive gears 40, 40′, respectively. The second drive gear 40′ isdriven by the drive input extension 32 that extends from the first side28 to the second side 29 of the cutter body 20. The dual sided gearassemblies 14, 14′, provide two propulsion gears 60, 60′ and two treadsthat may provide for more even and straight propulsion of the cutter 10with respect to a material. The treads 68, 68′ are configured onopposing sides of the blade 80 and rotate down to pinch material againstthe foot 90 having a width 96.

As shown in FIG. 9 an exemplary self-propelled cutter 10 has a driveassembly 14 that utilizes a single gear assembly 15 on a first side 28of the cutter body 20. A propulsion gear 60 is configured on a firstside 28 of the cutter body 20 and a propulsion gear extension 64 extendsfrom the first side 28 of the cutter body 20 to the second side 29 ofthe cutter body 20 through the propulsion gear body recess 65. Thepropulsion gear extension 64 couples with a second tread 68′ on thesecond side of the cutter body 20. This arrangement enables the firstset of gears and the lever arm 70 to move both the first and secondtreads 68, 68′ about the transfer gear 50 as required. The width 96 ofthe foot 90 is shown in FIG. 9.

As shown in FIG. 10, an exemplary self-propelled cutter 10 has twopropulsion gears 60, 60′ configured on opposing sides of the blade 80.The propulsion gears 60, 60′ rotate about the transfer gear. Asdescribed herein, the self-propelled cutter may track more easily in astraight line with treads on either side of the blade 80.

As shown in FIG. 11 an exemplary self-propelled cutter 10 has a tread 68with propulsion teeth 69 that is coupled with the propulsion gear 60.The propulsion teeth 69 extend out radially from the rotational axis 61of the propulsion gear a greater distance than the first propulsionengagement teeth 67. The propulsion teeth 69 resemble saw tooth bladeshaving individual portions and having an extended end or point andcurved, straight, or radiused sides.

As shown in FIG. 12, an exemplary self-propelled cutter 10 has a wormgear 46 that engages with the transfer gear 50. The drive input 30extends to the back 24 of the cutter 10 or cutter body 20. A drive inputdevice can be easily coupled with the drive input 30 to propel thecutter forward. A drive input device 31, such as an electric motor 37may be coupled with the drive input 30 to turn the drive input extension32, that has a rotational axis 41 that is orthogonal to the rotationalaxis 51 of the transfer gear 50, or extends along the length of thecutter body 20. The electric motor may have an input interface 38 suchas a socket having planar surfaces to couple with or mate with theplanar surfaces on the drive input 30. The electric motor may spin themating socket to turn the drive input and gear assembly of the cutter10. The electric motor may have an on/off button 39 to control themovement of the cutter 10 over a material to be cut.

Referring now to FIGS. 13 to 20, an exemplary self-propelled cutter 10is configured with a drive assembly 14 that couples with a handle 35 anddrive input 30. The handle is rotated to rotate the drive input 30 andthe first drive gear 40 is attached to the drive input. The first drivegear 40 engages with the first transfer gear 50, both on the first side28, or drive side of the self-propelled cutter body 10. A transfer gearextension 55 extends as an axle from the first transfer gear 50 to asecond transfer gear 56, configured on a second side 29 of theself-propelled cutter body 20, or second side of the blade 80. Thesecond transfer gear 56 engages with a first propulsion gear 60 thatdrives a propulsion gear extension 64, or axle that drives both thefirst tread 68, coupled to the first propulsion gear and a second tread66, configured on a first side 28 of the cutter body 20. The driveassembly is configured with two lever arms 70′, 70 on the drive or firstside 28 and on the second side 29, respectively. Lever arm 70 extends onthe second side 29 from the propulsion gear axle, or propulsion gearextension 64, to the transfer gear extension 55. The lever arm 70′extends on the first side from the propulsion gear extension 64 to thetransfer gear extension 55, therefore the two lever arms 70, 70′ move inunison to keep the two treads engaged with the material to be cut.

As shown in FIG. 14, the blade 80 is configured between the first tread68 and the second tread 66.

As shown in FIG. 17, the exemplary drive assembly 14 is in a down anddrive configuration and the handle 35 is being turned to pivot the leverarm 70 as indicated by the bold curved arrow. The lever arm 70 ispivoted down to engage a material being fed over the foot and into thecutter 10. As shown in FIG. 18, the tread 68 is up from the foot 90 andthe lever arm 70 is pivoted up.

FIG. 19 shows the self-propelled cutter 10 shown in FIGS. 13-18 and20-21 with the cover 12 configured thereon.

Referring now to FIGS. 20 and 21, an exemplary drive assembly 14comprises a first transfer gear 50 that is on a first side, or driveinput side, of the cutter body, (not shown), a transfer gear extension55 that extends to a second transfer gear 56, on a second side of thecutter body. The second transfer gear 56 engages with the firstpropulsion gear 60 through the gear teeth 57 of the second transfer gear56 engaging with the engagement teeth 67 of the first propulsion gear. Atread 68 is coupled with the first propulsion gear and has propulsionteeth that extend radially out beyond the engagement teeth 67 of thefirst propulsion gear. The lever arm 70 is coupled between the firstpropulsion gear and the second transfer gear 56, and holds these twogears in engagement. The lever arm 70 pivots around the transfer gearextension 55, or rotation axis 51 of the second transfer gear 56, andthe propulsion gear extension 64, or rotational axis of the propulsiongear 61. A spring receiver recess 85 is shown in the lever arm 70 inFIG. 20, and a spring 86 is configured in the spring recess in FIG. 21.The spring extends from the spring recess to an extended end 87 of thespring that is configured to interface with the housing or cover toprovide a spring force on the lever arm 70 and to act as a back-stop 26for the lever arm 70, thereby preventing the lever arm 70 from rotatingup about the propulsion transfer gear rotation axis 51.

It will be apparent to those skilled in the art that variousmodifications, combinations and variations can be made in the presentinvention without departing from the scope of the invention. Specificembodiments, features and elements described herein may be modified,and/or combined in any suitable manner. Thus, it is intended that thepresent invention cover the modifications, combinations and variationsof this invention provided they come within the scope of the appendedclaims and their equivalents.

What is claimed is:
 1. A propelled cutter comprising: a) a cutter bodycomprising: i) a first side; and ii) a second side; iii) a front; iv) aback; v) a bottom; vi) a top; and vii) a vertical axis extending fromsaid bottom to said top when in an upright position; b) a fixed bladecoupled to the cutter body; c) a foot extending from said bottom of thecutter body and configured to guide a material to be cut over the footand across the fixed blade; d) a drive input coupled with a driveextension that is coupled with the cutter body and with a driveassembly, said drive assembly comprising: iii) a first propulsion gearconfigured on the first side of the cutter body and having a rotationalaxis; iv) a first transfer gear configured on the first side of thecutter body and having a rotational axis and being movably attached andmovably engaged with the first propulsion gear to spin the propulsiongear; wherein the rotational axis of the first propulsion gear isconfigured at an offset angle of between 0 and 90 degrees extendingtoward the back of the cutter body from the vertical axis extendingthrough the rotational axis of the transfer gear; wherein the propulsiongear is configured more proximal to the back and the bottom of thecutter body than the first transfer gear; wherein the first propulsiongear is driven by the first transfer gear to spin to move said materialto be cut across the fixed blade to cut said material.
 2. The propelledcutter of claim 1, wherein the drive assembly further comprises a firstdrive gear on the first side of the cutter body that is coupled with thedrive input and engaged with the first transfer gear, and wherein thetransfer gear is movably engaged between the first drive gear and thefirst propulsion gear.
 3. The propelled cutter of claim 1, wherein thefirst propulsion gear comprises a tread that extends radially outwardaround an outer diameter of the first propulsion gear, wherein the treadengages with said material to move said material.
 4. The propelledcutter of claim 1, wherein the drive assembly further comprises a firstlever arm extending between and attached to the first transfer gear andthe first propulsion gear; wherein the lever arm is rotationally engagedwith the first transfer gear and rotates about the first transfer gearto move the first propulsion gear circumferentially about the firsttransfer gear; wherein the first lever arm rotates about a rotationalaxis of the first transfer gear; wherein the first lever arm provides aforce on first propulsion gear to move said material to be cut acrossthe fixed blade.
 5. The propelled cutter of claim 4, wherein the driveassembly further comprises a second lever arm that extends on the secondside of the cutter body from the propulsion gear extension to thetransfer gear extension.
 6. The propelled cutter of claim 1, wherein thedrive assembly further comprises a second propulsion gear configured onthe second side of the cutter body.
 7. The propelled cutter of claim 6,wherein the drive assembly further comprises a first drive gear that iscoupled with the drive input and wherein the first drive gear is on thefirst side of the cutter body having the drive input and is engaged withthe first transfer gear.
 8. The propelled cutter of claim 7, wherein thedrive assembly further comprises a second transfer gear and a secondpropulsion gear configured on the second side of the cutter body and atransfer gear extension, extending through the cutter body and coupledwith the first transfer gear and the second transfer gear; wherein thesecond transfer gear is movably attached with the second propulsion gearto spin the propulsion gear.
 9. The propelled cutter of claim 8, whereinthe second propulsion gear is engaged with the second transfer gear onthe second side of the cutter body.
 10. The propelled cutter of claim 9,further comprising: a propulsion gear extension that extends from thefirst propulsion gear on the first side of the cutter body, and a treadon the first side of the cutter body and coupled to the first propulsiongear by said propulsion gear extension, wherein the propulsion gearextension extends along the rotation axis of the propulsion gear. 11.The propelled cutter of claim 1, wherein the foot extends forward thefixed blade.
 12. The propelled cutter of claim 1, further comprising adrive input device coupled with the drive input to rotate the driveinput and thereby rotate the first transfer gear which rotates the firstpropulsion gear.
 13. The propelled cutter of claim 12, wherein the driveinput device is an electric motor coupled with the drive input.
 14. Thepropelled cutter of claim 1, further comprising a front-stop extendingfrom the cutter body to prevent the propulsion gear from rotatingforward with respect to the transfer gear.
 15. The propelled cutter ofclaim 1, further comprising a back-stop extending from the cutter bodyin a position more proximal to the back of the cutter body than thepropulsion gear to prevent the propulsion gear from rotating backwardwith respect to the transfer gear.